1. Field of the Invention
The present invention relates to a method and apparatus for forming sealing elements on a variety of fastening devices and novel sealing and retaining devices resulting therefrom. More particularly, the present invention relates to an automated method and apparatus for forming a compressible sealing element on and extending from a metal fastener such as a clip, that prohibits air and moisture transfer between the top and bottom portions of the clip, and yet allows both portions of the clip to remain flexible for easy installation into a finished assembly. The present invention further relates to a method and apparatus for forming a sealing element on a fastening device, such as a metal clip, wherein the sealing element contains a region that permits installation thereof into a finished article with low installation force.
2. Description of the Related Art
Fastening devices such as metal retaining clips are extensively used in various articles of manufacture. Such devices have for many years, provided a reliable, efficient and cost effective way of grasping and retaining one material and joining it to a separate substrate. An example of a metal clip that is prevalently used in the automobile industry is a T-shaped clip that has a central clip on its lower portion for anchoring it to a substrate, and two smaller spaced clips at the outer edges of the upper portion thereof for receiving and retaining material and thereby joining it to the substrate. One of the many uses of such metal retaining clips is joining trim to the interior of a vehicle door frame. In this example, the lower central clip engages the door frame and the upper spaced clips engage and anchor the door trim to the clip, and thereby the frame.
One of the drawbacks associated with use of metal clips of the type described above, is that they are often installed in places where they will encounter water or moisture. Due to the irregular shape of the clips, once they are installed they leave voids where moisture can transfer from the upper portion of the clip to the lower portion of the clip and the hole that it is pressed into. Such occurrences can lead to a collection of liquid or moisture in the hole and/or further negative effects that can result from a door frame or other parts being exposed to moisture or liquids over an extended period of time. In addition to these problems, the clips do not lessen sound transmission between the lower portion of the clip and the upper portion, and are also susceptible to rattling or loosening as a result of vibration or impact. All of these occurrences obviously present undesirable drawbacks in an automobile or other article of manufacture that utilize such clips.
In order to overcome these drawbacks, several solutions have been proposed. However, none of the solutions has had the attributes of being sufficiently reliable and economical. A number of solutions have involved the application of a sealing device on a clip between the top and bottom portions thereof, in order to allow a receiving hole that the clip is pressed into to be sealed in a water-tight manner. These known solutions for adding a sealing element to metal retaining clips, however, have all presented some rather significant problems. To begin with, such sealing devices have required a preformed element to be first manually installed on the clip. The process of manual installation has been slow, costly and lends itself to installation problems, such as alignment difficulties. In addition, manual installation of such elements requires a relatively precise tolerance that frequently is not present, in order to have the sealing device be close enough to the clip so that it will be retained and yet loose enough to permit initial installation. Most all of the manually installed sealing elements of the prior art have required a subsequent heating or baking step in order to adhere them and form a water tight seal on the clip.
The difficulties encountered in attempting to properly manually install such sealing elements on the clips were frequently compounded when the entire assembly was subjected to heating. The end result was often uneven or incomplete adherence of the device to the clip surface insufficient to form a water tight seal therewith. In instances where such a seal was achieved, the clip often did not remain sufficiently flexible to permit easy installation. An additional problem facing such prior art assemblies was the fact that once the sealing element was formed on the clip, the clip then had to be installed into an article such as a door frame by exerting a sufficient amount of force to overcome the spring bias of the clip. This process often required a significant installation force to be placed on the clip and at least a portion of the sealing element thereon. The application of such installation forces often compromised the sealing between the element and the clip causing it to weaken or tear away. This resulted in an interruption of the moisture proof seal between the sealing device and the clip and rendering the assembly unfit for use.
As a result of the foregoing is apparent that a need exists for a simple, efficient and automated apparatus and method for forming a sealing element on a fastener such as a clip. It is further apparent that the need exists for an improved sealing element on a metal clip that adheres as well or better than prior art designs, and provides a construction that permits installation of the clip with low installation force without compromising the sealing action and leaves the clip sufficiently flexible for easy installation. It is the purpose of the present invention to fulfill the above described needs in the art, as well as other needs apparent to the skilled artisan from the following detailed description of this invention.